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IP subnet calculator

Type an address with its prefix or mask to see the network, its usable range and masks. Split it into smaller subnets, or look up any prefix in the reference tables.

Network200.0.0.0/7
Usable hosts33,554,430
Subnet mask254.0.0.0
Addresses33,554,432
Network address
200.0.0.0
Broadcast address
201.255.255.255
First usable
200.0.0.1
Last usable
201.255.255.254
Usable hosts
33,554,430 (33,554,432 less the network and broadcast addresses)
Subnet mask
254.0.0.0
Wildcard mask
1.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/7
Type
Public public
Old class
C (default /24)
As numbers
Hex C8000000 · Integer 3355443200 to 3388997631
Reverse DNS zones
200.in-addr.arpa
201.in-addr.arpa
/7 is not on a 8-bit boundary, so it takes 2 /8 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11001000.00000000.00000000.00000000200.0.0.0
Subnet mask11111110.00000000.00000000.00000000254.0.0.0
Network11001000.00000000.00000000.00000000200.0.0.0
Broadcast11001001.11111111.11111111.11111111201.255.255.255
Split into smaller subnets/14
/8 (2)/9 (4)/10 (8)/11 (16)/12 (32)/13 (64)/14 (128)/15 (256)/16 (512)/17 (1,024)/18 (2,048)/19 (4,096)

200.0.0.0/7 makes 128 subnets of /14.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1200.0.0.0/14200.0.0.1 to 200.3.255.254200.3.255.255262,142
2200.4.0.0/14200.4.0.1 to 200.7.255.254200.7.255.255262,142
3200.8.0.0/14200.8.0.1 to 200.11.255.254200.11.255.255262,142
4200.12.0.0/14200.12.0.1 to 200.15.255.254200.15.255.255262,142
5200.16.0.0/14200.16.0.1 to 200.19.255.254200.19.255.255262,142
6200.20.0.0/14200.20.0.1 to 200.23.255.254200.23.255.255262,142
7200.24.0.0/14200.24.0.1 to 200.27.255.254200.27.255.255262,142
8200.28.0.0/14200.28.0.1 to 200.31.255.254200.31.255.255262,142
9200.32.0.0/14200.32.0.1 to 200.35.255.254200.35.255.255262,142
10200.36.0.0/14200.36.0.1 to 200.39.255.254200.39.255.255262,142
11200.40.0.0/14200.40.0.1 to 200.43.255.254200.43.255.255262,142
12200.44.0.0/14200.44.0.1 to 200.47.255.254200.47.255.255262,142
13200.48.0.0/14200.48.0.1 to 200.51.255.254200.51.255.255262,142
14200.52.0.0/14200.52.0.1 to 200.55.255.254200.55.255.255262,142
15200.56.0.0/14200.56.0.1 to 200.59.255.254200.59.255.255262,142
16200.60.0.0/14200.60.0.1 to 200.63.255.254200.63.255.255262,142
17200.64.0.0/14200.64.0.1 to 200.67.255.254200.67.255.255262,142
18200.68.0.0/14200.68.0.1 to 200.71.255.254200.71.255.255262,142
19200.72.0.0/14200.72.0.1 to 200.75.255.254200.75.255.255262,142
20200.76.0.0/14200.76.0.1 to 200.79.255.254200.79.255.255262,142
21200.80.0.0/14200.80.0.1 to 200.83.255.254200.83.255.255262,142
22200.84.0.0/14200.84.0.1 to 200.87.255.254200.87.255.255262,142
23200.88.0.0/14200.88.0.1 to 200.91.255.254200.91.255.255262,142
24200.92.0.0/14200.92.0.1 to 200.95.255.254200.95.255.255262,142
25200.96.0.0/14200.96.0.1 to 200.99.255.254200.99.255.255262,142
26200.100.0.0/14200.100.0.1 to 200.103.255.254200.103.255.255262,142
27200.104.0.0/14200.104.0.1 to 200.107.255.254200.107.255.255262,142
28200.108.0.0/14200.108.0.1 to 200.111.255.254200.111.255.255262,142
29200.112.0.0/14200.112.0.1 to 200.115.255.254200.115.255.255262,142
30200.116.0.0/14200.116.0.1 to 200.119.255.254200.119.255.255262,142
31200.120.0.0/14200.120.0.1 to 200.123.255.254200.123.255.255262,142
32200.124.0.0/14200.124.0.1 to 200.127.255.254200.127.255.255262,142
33200.128.0.0/14200.128.0.1 to 200.131.255.254200.131.255.255262,142
34200.132.0.0/14200.132.0.1 to 200.135.255.254200.135.255.255262,142
35200.136.0.0/14200.136.0.1 to 200.139.255.254200.139.255.255262,142
36200.140.0.0/14200.140.0.1 to 200.143.255.254200.143.255.255262,142
37200.144.0.0/14200.144.0.1 to 200.147.255.254200.147.255.255262,142
38200.148.0.0/14200.148.0.1 to 200.151.255.254200.151.255.255262,142
39200.152.0.0/14200.152.0.1 to 200.155.255.254200.155.255.255262,142
40200.156.0.0/14200.156.0.1 to 200.159.255.254200.159.255.255262,142
41200.160.0.0/14200.160.0.1 to 200.163.255.254200.163.255.255262,142
42200.164.0.0/14200.164.0.1 to 200.167.255.254200.167.255.255262,142
43200.168.0.0/14200.168.0.1 to 200.171.255.254200.171.255.255262,142
44200.172.0.0/14200.172.0.1 to 200.175.255.254200.175.255.255262,142
45200.176.0.0/14200.176.0.1 to 200.179.255.254200.179.255.255262,142
46200.180.0.0/14200.180.0.1 to 200.183.255.254200.183.255.255262,142
47200.184.0.0/14200.184.0.1 to 200.187.255.254200.187.255.255262,142
48200.188.0.0/14200.188.0.1 to 200.191.255.254200.191.255.255262,142
49200.192.0.0/14200.192.0.1 to 200.195.255.254200.195.255.255262,142
50200.196.0.0/14200.196.0.1 to 200.199.255.254200.199.255.255262,142
51200.200.0.0/14200.200.0.1 to 200.203.255.254200.203.255.255262,142
52200.204.0.0/14200.204.0.1 to 200.207.255.254200.207.255.255262,142
53200.208.0.0/14200.208.0.1 to 200.211.255.254200.211.255.255262,142
54200.212.0.0/14200.212.0.1 to 200.215.255.254200.215.255.255262,142
55200.216.0.0/14200.216.0.1 to 200.219.255.254200.219.255.255262,142
56200.220.0.0/14200.220.0.1 to 200.223.255.254200.223.255.255262,142
57200.224.0.0/14200.224.0.1 to 200.227.255.254200.227.255.255262,142
58200.228.0.0/14200.228.0.1 to 200.231.255.254200.231.255.255262,142
59200.232.0.0/14200.232.0.1 to 200.235.255.254200.235.255.255262,142
60200.236.0.0/14200.236.0.1 to 200.239.255.254200.239.255.255262,142
61200.240.0.0/14200.240.0.1 to 200.243.255.254200.243.255.255262,142
62200.244.0.0/14200.244.0.1 to 200.247.255.254200.247.255.255262,142
63200.248.0.0/14200.248.0.1 to 200.251.255.254200.251.255.255262,142
64200.252.0.0/14200.252.0.1 to 200.255.255.254200.255.255.255262,142
65201.0.0.0/14201.0.0.1 to 201.3.255.254201.3.255.255262,142
66201.4.0.0/14201.4.0.1 to 201.7.255.254201.7.255.255262,142
67201.8.0.0/14201.8.0.1 to 201.11.255.254201.11.255.255262,142
68201.12.0.0/14201.12.0.1 to 201.15.255.254201.15.255.255262,142
69201.16.0.0/14201.16.0.1 to 201.19.255.254201.19.255.255262,142
70201.20.0.0/14201.20.0.1 to 201.23.255.254201.23.255.255262,142
71201.24.0.0/14201.24.0.1 to 201.27.255.254201.27.255.255262,142
72201.28.0.0/14201.28.0.1 to 201.31.255.254201.31.255.255262,142
73201.32.0.0/14201.32.0.1 to 201.35.255.254201.35.255.255262,142
74201.36.0.0/14201.36.0.1 to 201.39.255.254201.39.255.255262,142
75201.40.0.0/14201.40.0.1 to 201.43.255.254201.43.255.255262,142
76201.44.0.0/14201.44.0.1 to 201.47.255.254201.47.255.255262,142
77201.48.0.0/14201.48.0.1 to 201.51.255.254201.51.255.255262,142
78201.52.0.0/14201.52.0.1 to 201.55.255.254201.55.255.255262,142
79201.56.0.0/14201.56.0.1 to 201.59.255.254201.59.255.255262,142
80201.60.0.0/14201.60.0.1 to 201.63.255.254201.63.255.255262,142
81201.64.0.0/14201.64.0.1 to 201.67.255.254201.67.255.255262,142
82201.68.0.0/14201.68.0.1 to 201.71.255.254201.71.255.255262,142
83201.72.0.0/14201.72.0.1 to 201.75.255.254201.75.255.255262,142
84201.76.0.0/14201.76.0.1 to 201.79.255.254201.79.255.255262,142
85201.80.0.0/14201.80.0.1 to 201.83.255.254201.83.255.255262,142
86201.84.0.0/14201.84.0.1 to 201.87.255.254201.87.255.255262,142
87201.88.0.0/14201.88.0.1 to 201.91.255.254201.91.255.255262,142
88201.92.0.0/14201.92.0.1 to 201.95.255.254201.95.255.255262,142
89201.96.0.0/14201.96.0.1 to 201.99.255.254201.99.255.255262,142
90201.100.0.0/14201.100.0.1 to 201.103.255.254201.103.255.255262,142
91201.104.0.0/14201.104.0.1 to 201.107.255.254201.107.255.255262,142
92201.108.0.0/14201.108.0.1 to 201.111.255.254201.111.255.255262,142
93201.112.0.0/14201.112.0.1 to 201.115.255.254201.115.255.255262,142
94201.116.0.0/14201.116.0.1 to 201.119.255.254201.119.255.255262,142
95201.120.0.0/14201.120.0.1 to 201.123.255.254201.123.255.255262,142
96201.124.0.0/14201.124.0.1 to 201.127.255.254201.127.255.255262,142
97201.128.0.0/14201.128.0.1 to 201.131.255.254201.131.255.255262,142
98201.132.0.0/14201.132.0.1 to 201.135.255.254201.135.255.255262,142
99201.136.0.0/14201.136.0.1 to 201.139.255.254201.139.255.255262,142
100201.140.0.0/14201.140.0.1 to 201.143.255.254201.143.255.255262,142
101201.144.0.0/14201.144.0.1 to 201.147.255.254201.147.255.255262,142
102201.148.0.0/14201.148.0.1 to 201.151.255.254201.151.255.255262,142
103201.152.0.0/14201.152.0.1 to 201.155.255.254201.155.255.255262,142
104201.156.0.0/14201.156.0.1 to 201.159.255.254201.159.255.255262,142
105201.160.0.0/14201.160.0.1 to 201.163.255.254201.163.255.255262,142
106201.164.0.0/14201.164.0.1 to 201.167.255.254201.167.255.255262,142
107201.168.0.0/14201.168.0.1 to 201.171.255.254201.171.255.255262,142
108201.172.0.0/14201.172.0.1 to 201.175.255.254201.175.255.255262,142
109201.176.0.0/14201.176.0.1 to 201.179.255.254201.179.255.255262,142
110201.180.0.0/14201.180.0.1 to 201.183.255.254201.183.255.255262,142
111201.184.0.0/14201.184.0.1 to 201.187.255.254201.187.255.255262,142
112201.188.0.0/14201.188.0.1 to 201.191.255.254201.191.255.255262,142
113201.192.0.0/14201.192.0.1 to 201.195.255.254201.195.255.255262,142
114201.196.0.0/14201.196.0.1 to 201.199.255.254201.199.255.255262,142
115201.200.0.0/14201.200.0.1 to 201.203.255.254201.203.255.255262,142
116201.204.0.0/14201.204.0.1 to 201.207.255.254201.207.255.255262,142
117201.208.0.0/14201.208.0.1 to 201.211.255.254201.211.255.255262,142
118201.212.0.0/14201.212.0.1 to 201.215.255.254201.215.255.255262,142
119201.216.0.0/14201.216.0.1 to 201.219.255.254201.219.255.255262,142
120201.220.0.0/14201.220.0.1 to 201.223.255.254201.223.255.255262,142
121201.224.0.0/14201.224.0.1 to 201.227.255.254201.227.255.255262,142
122201.228.0.0/14201.228.0.1 to 201.231.255.254201.231.255.255262,142
123201.232.0.0/14201.232.0.1 to 201.235.255.254201.235.255.255262,142
124201.236.0.0/14201.236.0.1 to 201.239.255.254201.239.255.255262,142
125201.240.0.0/14201.240.0.1 to 201.243.255.254201.243.255.255262,142
126201.244.0.0/14201.244.0.1 to 201.247.255.254201.247.255.255262,142
127201.248.0.0/14201.248.0.1 to 201.251.255.254201.251.255.255262,142
128201.252.0.0/14201.252.0.1 to 201.255.255.254201.255.255.255262,142

IPv4 CIDR reference (/0 to /32)

IPv4 prefix lengths
PrefixSubnet maskWildcardAddressesUsable hostsSizeTypical use
/00.0.0.0255.255.255.2554,294,967,2964,294,967,29416,777,216 × /24
/1128.0.0.0127.255.255.2552,147,483,6482,147,483,6468,388,608 × /24
/2192.0.0.063.255.255.2551,073,741,8241,073,741,8224,194,304 × /24
/3224.0.0.031.255.255.255536,870,912536,870,9102,097,152 × /24
/4240.0.0.015.255.255.255268,435,456268,435,4541,048,576 × /24
/5248.0.0.07.255.255.255134,217,728134,217,726524,288 × /24
/6252.0.0.03.255.255.25567,108,86467,108,862262,144 × /24
/7254.0.0.01.255.255.25533,554,43233,554,430131,072 × /24
/8255.0.0.00.255.255.25516,777,21616,777,21465,536 × /24Old class A; 10.0.0.0/8
/9255.128.0.00.127.255.2558,388,6088,388,60632,768 × /24
/10255.192.0.00.63.255.2554,194,3044,194,30216,384 × /24
/11255.224.0.00.31.255.2552,097,1522,097,1508,192 × /24
/12255.240.0.00.15.255.2551,048,5761,048,5744,096 × /24172.16.0.0/12
/13255.248.0.00.7.255.255524,288524,2862,048 × /24
/14255.252.0.00.3.255.255262,144262,1421,024 × /24
/15255.254.0.00.1.255.255131,072131,070512 × /24
/16255.255.0.00.0.255.25565,53665,534256 × /24Old class B; 192.168.0.0/16
/17255.255.128.00.0.127.25532,76832,766128 × /24
/18255.255.192.00.0.63.25516,38416,38264 × /24
/19255.255.224.00.0.31.2558,1928,19032 × /24
/20255.255.240.00.0.15.2554,0964,09416 × /24
/21255.255.248.00.0.7.2552,0482,0468 × /24
/22255.255.252.00.0.3.2551,0241,0224 × /24Large office or guest Wi-Fi (1,022 hosts)
/23255.255.254.00.0.1.2555125102 × /24Larger office LAN (510 hosts)
/24255.255.255.00.0.0.2552562541 × /24Typical office LAN (old class C)
/25255.255.255.1280.0.0.1271281261/2 of a /24Smaller LAN or VLAN
/26255.255.255.1920.0.0.6364621/4 of a /24Smaller LAN or VLAN
/27255.255.255.2240.0.0.3132301/8 of a /24Small VLAN, phones, cameras
/28255.255.255.2400.0.0.1516141/16 of a /24Small VLAN, phones, cameras
/29255.255.255.2480.0.0.7861/32 of a /24Small fixed public block (5 usable)
/30255.255.255.2520.0.0.3421/64 of a /24Point-to-point (old style)
/31255.255.255.2540.0.0.1221/128 of a /24Point-to-point link (RFC 3021)
/32255.255.255.2550.0.0.0111/256 of a /24One host

IPv6 prefix reference

IPv6 prefix lengths
PrefixAddresses/64 LANs/48 sitesNibbleTypical use
/342,535,295,865,117,307,932,921,825,928,971,026,432 (2^125)2,305,843,009,213,693,95235,184,372,088,832NoAll global unicast (2000::/3)
/165,192,296,858,534,827,628,530,496,329,220,096 (2^112)281,474,976,710,6564,294,967,296Yes
/20324,518,553,658,426,726,783,156,020,576,256 (2^108)17,592,186,044,416268,435,456YesLarge provider allocation (RIPE minimum for some)
/29633,825,300,114,114,700,748,351,602,688 (2^99)34,359,738,368524,288NoRIPE allocation to a provider (often)
/3279,228,162,514,264,337,593,543,950,336 (2^96)4,294,967,29665,536YesProvider allocation (RIPE default)
/364,951,760,157,141,521,099,596,496,896 (2^92)268,435,4564,096Yes
/40309,485,009,821,345,068,724,781,056 (2^88)16,777,216256Yes
/4419,342,813,113,834,066,795,298,816 (2^84)1,048,57616Yes
/481,208,925,819,614,629,174,706,176 (2^80)65,5361YesOne site or organisation (RIPE PI / assignment)
/5275,557,863,725,914,323,419,136 (2^76)4,096Yes
/564,722,366,482,869,645,213,696 (2^72)256YesSmall site or home (common provider assignment)
/60295,147,905,179,352,825,856 (2^68)16YesSome home broadband (16 LANs)
/6418,446,744,073,709,551,616 (2^64)1YesOne LAN or VLAN (needed for SLAAC)
/7272,057,594,037,927,936 (2^56)1/256 of a /64Yes
/80281,474,976,710,656 (2^48)1/65,536 of a /64Yes
/964,294,967,2961/4,294,967,296 of a /64YesEmbeds an IPv4 address (NAT64)
/11265,5361/281,474,976,710,656 of a /64Yes
/1202561/72,057,594,037,927,936 of a /64Yes
/124161/1,152,921,504,606,846,976 of a /64Yes
/12641/4,611,686,018,427,387,904 of a /64No
/12721/9,223,372,036,854,775,808 of a /64NoPoint-to-point link (RFC 6164)
/12811/18,446,744,073,709,551,616 of a /64YesOne host or loopback

Private and special ranges

IPv4

Special-purpose ranges
RangeNameWhat it is
255.255.255.255/32Limited broadcastEvery host on the local network
0.0.0.0/8This networkNot routed; 0.0.0.0 means "any address" in settings
10.0.0.0/8Private (RFC 1918)Office and home networks; not routed on the internet
100.64.0.0/10Shared address space (CGNAT)Used by providers behind carrier-grade NAT (RFC 6598)
127.0.0.0/8LoopbackThis computer
169.254.0.0/16Link-local (APIPA)Self-assigned when no DHCP server answers
172.16.0.0/12Private (RFC 1918)Office and home networks; not routed on the internet
192.0.0.0/24IETF protocol assignmentsSpecial uses such as DS-Lite
192.0.2.0/24Documentation (TEST-NET-1)For examples; never used on a network
192.88.99.0/246to4 relay (deprecated)Formerly anycast for 6to4
192.168.0.0/16Private (RFC 1918)Office and home networks; not routed on the internet
198.18.0.0/15BenchmarkingNetwork equipment testing (RFC 2544)
198.51.100.0/24Documentation (TEST-NET-2)For examples; never used on a network
203.0.113.0/24Documentation (TEST-NET-3)For examples; never used on a network
224.0.0.0/4MulticastOne-to-many traffic, such as IPTV and routing protocols
240.0.0.0/4ReservedFuture use; not usable on most systems

IPv6

Special-purpose ranges
RangeNameWhat it is
::/128UnspecifiedNo address; :: means "any address" in settings
::1/128LoopbackThis computer
::ffff:0:0/96IPv4-mappedAn IPv4 address written as IPv6
64:ff9b::/96NAT64IPv4 addresses reached through a NAT64 gateway
100::/64Discard onlyTraffic sent here is dropped (RFC 6666)
2001:db8::/32DocumentationFor examples; never used on a network
2001::/32TeredoIPv6 tunnelled over IPv4 UDP
2002::/166to4IPv6 tunnelled over IPv4 (largely retired)
3fff::/20DocumentationFor examples (RFC 9637)
fc00::/7Unique local (ULA)Private IPv6, like RFC 1918; usually fd00::/8
fe80::/10Link-localEvery IPv6 interface has one; not routed
ff00::/8MulticastOne-to-many traffic; replaces broadcast
2000::/3Global unicastPublic internet addresses

About this tool

A network is written as an address and a prefix length, such as 192.168.1.0/24: the first 24 bits name the network and the rest number the devices on it. The calculator works out where the network starts and ends, how many devices it holds, its subnet and wildcard masks, and the reverse DNS zone to ask your provider for.

It also splits a network into equal smaller ones (one per VLAN or site), turns a range of addresses into the fewest CIDR blocks for a firewall rule, and lists every IPv4 prefix length and the common IPv6 ones in reference tables.

Common questions

Why are two addresses lost in every IPv4 subnet?

The first address names the network and the last is the broadcast address, so a /24 has 256 addresses but 254 for devices. A /31 (a link between two routers) and a /32 (one host) are the exceptions.

What size of IPv6 network should a LAN use?

Always /64. Devices pick their own address within it (SLAAC), which needs the full 64 bits. A site usually gets a /48 or /56 from its provider, which holds 65,536 or 256 LANs.

What is a wildcard mask?

The subnet mask turned inside out: 255.255.255.0 becomes 0.0.0.255. Cisco access lists and OSPF use it to say which bits must match.

Which ranges can I use inside an office?

IPv4: 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16. IPv6: unique local addresses from fd00::/8, though most networks use the public prefix from their provider.